Process of manufacturing open or closed packagings of foam plastics,preferably foam polystyrene

ABSTRACT

A process of manufacturing packages form rigid-type foam plastics, preferable foam polystyrene. Such surfaces as are to be joined are heated by direct contact with movable heating jaws until the desired surface configuration having a layer of molten material thereon has been obtained. The surfaces are then immediately put together and subjected to pressure. After the surfaces have been pressed together a shaping member can be urged against them to shape the joint and wipe any excess molten material therefrom. The heating jaw surfaces are preferably oblique relative to the plane of the surfaces to be joined, whereby the surfaces are bevelled and enlarged to produce a high strength, overlapped weld joint. The surfaces to be joined may also be formed with alternating ridges and valleys to further increase the area of the surfaces joined.

March- 26, 1974 s. E. M. SOLLERUD 3,799,820

PROCESS OF MANUFACTURING OPEN OR CLOSED PACKAGINGS 0F FOAM PLASTICS,PREFERABLY FOAM POLYSTYRENE Filed Jan. 18, 1972 10 Sheets-Sheet l Match26, 1974 s. E. M. SOLLERUD 3,799,320

PHQCESS OF MANUFACTURING OPEN OR CLOSED PACKAGINGS OF FOAM PLASTICS,PREFERABLY FOAI POLYSTYRENE Filed Jan. 18, 1972 10 Sheets-Sheet 2 March26, 1974 s. E. M. SOLLERUD 3,799,320

PROCESS OF MANUFACTURING OPEN OR CLOSED PACKAGINGS OF FORM PLASTICS,PREFERABLY FOAM POLYSTYRENE Filed Jan. 18, 1972 10 Sheets-Sheet :5

3,799,820 memes OF FOAM ENE , S. E. M. SOLLERUD MANUFACTURING OPEN ORCLOSED PAC PLASTICS PREFERABLY FOAM POLYSTYR l0 Sheets-Sheet 4 FiledJan. 18, 1972 MN MW Filed Jan. 18, 1972 March 26, 1974 s. E. M. SOLLERUD3,799,320

PROCESS OF MANUFACTURING OPEN OR CLOSED PACKAGINGS 0F FOAM PLASTICS,PREFERABLY FOAM POLYSTYRENE l0 Sheets-Sheet 5 ln m March 26, 1974 s. E.M. SOLLERUD 3,799,820

PROCESS OF MANUFACTURING OPEN OR CLOSED PACKAGINGS 0F FOAM PLASTICS,PREFERABLY FOAM PQLYSTYRENE Filed Jan. 18, 1972 10 Sheets-Sheet 6 March26, 1974 s. E. M. SOLLERUD 3,799,320

PROCESS OF MANUFACTURING OPEN OR CLOSED PACKAGINGS OF FOAM PLASTICS,PREFERABLY FOAM PULYSTYRENE Filed Jan. 18, 1972 10 Sheets-Sheet 7 m 1914s. E. M. SOLLERUD 3,799,820

PROCESS OF MANUFACTURING OPEN OR CLOSED PACKAGINGS OF FOAM PLASTICS,PREFERABLY FOAM POLYS'IYRENE Filed Jan. 18 1972 10 Sheets-Sheet H March26, 1974 s. E. M. SOLLERUD 3,799,820

PROCESS OF MANUFACTURING OPEN OR CLOSED PACKAGINGS 0F FOAM PLASTICS,PREFERABLY FOAM POLYSTYRENE March 26, 1974 s. E. M. SOLLERUD 3,799,820

PROCESS OF MANUFACTURING OPEN OR CLOSED PACKAGINGS 0F FOAM PLASTICS,PREFERABLY FOAM POLYSTYRENE Filed Jan, 18 1972 10 Sheets-Sheet- 10F/G.I6

Patented Mar. 26, 1974 Int. or. 15651; 7/28; 1329c 27/00 US. Cl. 156-6921 Claims ABSTRACT OF THE DISCLOSURE A process of manufacturing packagesfrom rigid-type foam plastics, preferably foam polystyrene. Suchsurfaces as are to be joined are heated by direct contact with movableheating jaws until the desired surface configuration having a layer ofmolten material thereon has been obtained. The surfaces are thenimmediately put together and subjected to pressure. After the surfaceshave been pressed together a shaping member can be urged against them toshape the joint and wipe any excess molten material therefrom. Theheating jaw surfaces are preferably oblique relative to the plane of thesurfaces to be joined, whereby the surfaces are bevelled and enlarged toproduce a high strength, overlapped weld joint. The surfaces to bejoined may also be formed with alternating ridges and valleys to furtherincrease the area of the surfaces joined.

CROSS REFERENCE TO RELATED APPLICATION This is a continuation-in-part ofmy copending application Ser. No. 114,266, filed Feb. 10, 1971, entitledA Process of Manufacturing Open or Closed Packages of Foam Plastics,Preferably Foam Polystyrene, now abandoned.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to a process of manufacturing open or closed packages ofrigid-type foam plastic materials preferably foam polystyrene.

DESCRIPTION OF THE PRIOR ART In the packaging industry there has longbeen a trend to convert from the use of conventional packagingmaterials, such as cardboard or paper, sheet metal, and glass, todiflerent kinds of plastics. The plastics have established themselvesbest in ligthweight packages as substitutes for paper since plasticsfoils can now'be manufactured at competitive prices, can be sealed in asimple manner by welding, and possess a superior strength. In semi-rigidpackages, such as milk cartons, recourse has been made to a compromise,viz the combination of cardboard or paper and a plastic coating thereon.This solution, though rather expensive, has certain advantages. Rigidplastic packages are mainly used only to package more expensive consumergoods, since the cost of the packages is high; however, a

the bottle or can type, which have an insignificant weight compared totheir volume. While cardboard and paper packages are transported,practically without exception, in a collapsed state and are erected atthe place of filling packages of paper and cardboard having a plasticscoating are usually manufactured at the place of filling, the startingmaterial used being in the form of a plastic coated paper web. Had thisnot been the case, packages of this kind would hardly have maintainedthemselves on the market. Certain types of packages of plastic-coatedpaper or cardboard are handled like packages of paper or cardboard only,that is they are conveyed in a collapsed state and are erected at theplace of use. As already stated, the relatively rigid plastic packagesare often manufactured at the place of filling.

It is evident from the foregoing that there is a strong demand for acheap, relatively rigid lightweight plastic material from whichpackagings can be manufactured at a price comparable to that of acorresponding paperboard or cardboard carton. However, in order for sucha package to be competitive, it should be possible to ship the materialin sheets or rolls and the packages of various kinds, includinghermetically closed packages, should be easily manufactured at the placewhere the packages are filled. In that case, such plastic packages couldeffectively compete with most commerially available packages ofdifferent materials.

The desired material already occurs on the market, viz extruded foampolystyrene. The problem, however, is that it has not previously beenpossible to manufacture satisfactory packages, and particularly sealed,fluid tight packages, of this material at reasonable cost. Many attemptshave been made, and considerable sums have been spent on projects forproviding a useful package of foam polystyrene after it was establishedthat the material, per se, is not only inexpensive to manufacture butalso possesses good tightness and excellent insulating properties, whichlatter imply great advantages for instance in packaging deep-frozenproducts which in such packages could be kept at room temperature for aconsiderably longer time than what is possible with the conventionalcardboard packages or cartons. It has also been established that thematerial can be readily provided with print, also in multicolortechnique.

The primary difliculty in manufacturing packages of this excellentmaterial results from the fact that conventional plastic welding methodscannot be used primarily because of the insulating properties of thematerial. Thus if two pieces of foam polystyrene to be joined are placedin superimposed relation between two heating jaws, these jaws will onlymelt a groove in the sides of the pieces engaged by the jaws, while theabutting sides of the two pieces will not, or only in an extremelyinsignificant degree, adhere to one another. Other prior art methods offastening together plastic surfaces, for instance with the use ofultra-sonics and hot air, have also proved inapplicable for the abovereason.

One attempt to manufacture a package from foamed sheet polystyrene isillustrated in U .S. Pat. No. 3,411,969 which is directed to the conceptof forming a one-piece tray-type carton from a blank which is die cutfrom an extruded sheet of foam polystyrene. The side panel portions ofthe blank are folded upward by forcing the blank through a forming die,and a heated blade member is inserted into and drawn along each of thecorner joints from the bottom panel to the open top of the carton tomelt a portion of the polystyrene material along the joint as the cartonis forced through the folding die. The folding die forces the cornerstogether to form a welded joint as the melted surfaces pass over theheated blade. No provisions are made for sealing the carton fiap orcover.

discussed above may be employed to weld the corners of the open-toppedtray, it has been found to be a practical impossibility to avoid anopening, or hole, at the bottom of the weld, i.e., at each bottom cornerof the carton, in the commercial production of such cartons. Thisresults from the fact that the molten material required to form a goodweld must necessarily be produced by melting the adjacent portions ofthe foam plastic sheet. While an excess of material is provided for thispurpose in the side panel of the blank at a distance above the bottompanel, there can be no excess material at the extreme bottom of the weldadjacent the bottom panel, with the result that an opening is producedat the bottom corners of the tray. Further, these welds formed in thecorners of the tray, are particularly susceptible to fracture as aresult of bending loads produced by internal pressure or loading in thetray.

SUMMARY OF THE INVENTION The present invention, therefore, has for itsobject to provide an improved method of manufacturing packages ofvarious kinds from foam polystyrene or expanded plastic materials ofsimilar structure. This object is attained in a package assembled from aplurality of separately formed foam plastic members with the surfacesthereof to be joined simultaneously heated to the melting point of thematerial over the entire expanse by heating means which are brought indirect contact with said surfaces. The heating is continued until alayer of molten material is obtained which covers the entire surfaces tobe joined. The heating means are then removed and the surfaces to bejoined are immediately put together and subjected to compressionpressure, the rigidity of the plastics being such that it withstandssaid pressure without deformation at those points where it has not beenheated.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described morein detail hereinbelow with reference to the accompanying drawings whichshow an embodiment of the invention and illustrate a method ofmanufacturing a substantially parallelepiped container consisting ofseparate plastic webs constituting the side walls, the bottom and thecover, and which are joined together to form the completed package.

In the drawings:

FIGS. 1-3 are schematic plan views showing successive steps in themanufacture of the body portion of a package according to the presentinvention;

FIGS. 4-6 are vertical sectional views illustrating suc cessive steps inthe placement of the bottom and cover on the body portion;

FIG. 7 is a view illustrating a modification of a portion of thestructure shown in FIGS. 4-6;

FIG. 8 is a sectional view taken on lines 8-8 of FIG. 7;

FIGS. 9-11 are schematic views illustrating successive steps in themanufacture of the body portion of a package according to an alternateembodiment of the invention;

FIGS. 12-14 are vertical sectional views illustrating successive stepsin an alternate process for welding a corner on the body portion.

FIG. 15 is a sectional view illustrating one method of manufacturing acorner member of the type illustrated in FIGS. 12-14; and,

FIGS. 16 and 17 illustrate the use of a recloseable dispensing openingin a cover member of the type shown in FIGS. 12-15.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus illustrated inFIGS. 1-14 is part of a large machine for automatically performing theprocess of manufacturing packages of foam polystyrene in accordance withthe invention. Other portions of the machine such as the apparatus forsupplying and removing blanks and finished packages, respectively, thecontrol means, etc., are not shown to avoid crowding of the drawings.These devices may be of any conventional construction and, as such, formno part of the instant invention. FIGS. 1-8 of the drawings illustratethe manufacture of a rightangled parallelepiped container having sidewalls, bottom and cover formed from separate substantially planar blankmembers, while the carton illustrated in FIGS. 9 -14 has generallyrounded corners and employs a modified structure for the top and bottommembers. It is pointed out, however, that the invention is not limitedto any specific configuration, but may be employed tomanufacturepackages if any desired shape.

In FIG. 1, 10 designates an inner mold part or mandrel about which ablank 11 of foam polystyrene, which is intended for the manufacture ofthe side walls of a packaging, a-re to be shaped and welded together toform an open-ended tubular body member. The mandrel 10 is rectangular inhorizontal section except that one corner thereof is cut away forreasons that will be more apparent hereinbelow. The blank 11 of foampolystyrene sheet is wrapped around the mandrel 10 with the flangesresulting from the bending opposite two sides of the mandrel 10, whichmake a right angle with one another. The mandrel 10 is then moved in thedirection indicated by the arrow 12 so that the side of the blank facingaway from the mandrel 10 is caused to engage the inner side of anangular member 13. At each of the free ends of the flanges of theangular member 13 there is mounted a folding flap 14 and 15,respectively, which is operable by means of a piston and cylinder unit16a and 16b, respectively. After the mandrel 10 has been moved towardsthe angular member 13 a piston and cylinder unit 18 is actuated and aheating means 19 fastened to the piston rod of the unit 18 is movedtoward the mandrel 10. Movement of the heating means 19 is continueduntil the front end thereof is at a small distance from the bevelledcorner surface of the mandrel 10 as is shown in FIG. 2. The piston andcylinder units 16a and 16b are then actuated, whereby the folding flaps14, 15 connected therewith are caused to swing through an angle ofapproximately as shown in FIG. 2, the free ends of the blank placedabout the mandrel 10 being brought into engagement with the metalheating means 19, as is shown in FIG. 2. The surface of heating means 19is treated to prevent the molten polystyrene from sticking thereto, asby coating with Teflon, or by plating with silver. The front end of theheating means 19 tapers forwardly in order that the means shall beeasily retractable, which takes place after the plastics material hasbeen melted to such an extent that a layer of the molten material coversthe surfaces to be joined, at which moment the heating means 19 isretracted to the position shown in FIG. 1 by the action of the pistonand cylinder unit 18. At the same time two piston and cylinder units 17aand 17b, respectively, which are connected to the piston and cylinderunits 16a and 16b, are caused immediately to move those sides of theblank against the mandrel 10,

which did not before engage said mandrel (see FIG. 2). Simultaneously,the entire unit consisting of the mandrel 10, the folding flaps and thepiston and cylinder units, is swung counter-clockwise so that an angularpressing means 20, which is reciprocable by means of a piston andcylinder unit 21, will be located precisely opposite the surfaces justput together. The means 20 is pressed into fixed engagement with thecorner of the blank facing it, and is maintained in engagement with saidcorner until the surfaces joined are securely adhered to one another.The mandrel 10 is then moved away from the angular means in thedirection opposite to the arrow 12, and the blank 11, now in the form ofan open-ended tubular body, is removed from the apparatus after themandrel has been extracted.

The body blank 11 which has been removed from the mandrel 10 is thenbrought in position so as to be provided with a bottom in the apparatusshown in FIG. 4 in which the body blank 11 is positioned on a bottomsupport member 22 which is mounted for vertical movement by piston 22awhile the side walls of the blank are supported by mold side pieces 23.Disposed above the blank 11 is a holder plate 24 which, for instance byvacuum action, is able to retain a bottom plate 25 of foam polystyreneabove the blank 11. The plate 24 is movable in vertical direction byrods 26, as shown by the double arrow 27. In addition to the mold formedby the parts 22, 23, and 24, there are provided heating means 28 whichaccording to the double arrow 29 are reciprocable by piston and cylinderunts (not shown) in the same way as the heating means 19 in FIGS. 1-3.For greater clarity, only two such heating means 28 are shown, it beingunderstood two similar means (not shown) are arranged to heat the sidesextending parallel to the plane of the drawing in FIGS. 4-6.

The heating means 28 are of a width corresponding to the length of theside walls of the blank 11 so that each means heats the entireassociated edge surface. From an outer position shown in FIG. 6 theheating means 28 are moved to the position shown in FIG. 4, in which thefront ends of the four heating means 28 thus abut each other at thecomers, forming a hopper-shaped portion. After the heating means 28 haveoccupied this position the bottom plate 22 is moved upwardly and at thesame time the holder plate 24 downwardly so that the upper edges of theblank 11 are brought into engagement with the underside of the heatingmeans 28 simultaneously as the edge portions of the underside of thebottom plate 25 are brought into engagement with the upper side of saidmeans.

It appears from FIGS. 4-6 that the heating means are oblique to the edgesurface and the underside of the bottom plate, and the surfaces engagingthe heating means 28 will thus be bevelled at the melting, whereby alarger surface of engagement is formed between the bottom 25 and theblank 11. The blank 11 and the bottom 25 are maintained in engagementwith the heating means for a sufliciently long time in order that alayer of molten material of suitable thickness may beformed, and arethen removed at the same time, whereupon the bottom 25 and the blank 11are quickly moved together so that the molten layers will come incontact with one another. Pressure is exerted on the bottom plate 25 bymeans of the holder plate 24, and the blank 11 is sufiiciently rigid towithstand the pressure against the action exerted by the holder plate24. Disposed above the holder plate 24 is a pressing and shaping device30 which is then lowered by a suitable piston rod (not shown) over thejoint formed, when the blank 11 and the bottom 25 are brought togetherto round olf or shape said joint and to remove any excess of moltenmaterial which have escaped from the joint, as is illustrated in FIG. 6.

In the manner described in the foregoing there has been formed anopen-ended container which can then either be removed from the apparatusfor use as such or be turned in some conventional way and directlyfilled for instance with a liquid such as milk. A cover may then beplaced on the open end in the same way as was described with referenceto FIGS. 4-6, and the completed package can be removed from the machine.

FIGS. 7 and 8 show a modification of the heating means 28, which hasproved extremely advantageous in practice. Alternating ridges 31 andvalleys 32 forming a zig-zag or corrugated pattern are provided on thesurfaces of the heating means which are brought into engagement with thesurfaces to be joined. As will appear from FIG. 8, the ridges on onesurface register with the valleys in the opposite surface. When thesesurfaces of the heating means are employed to heat surfaces to bejoined, conforming ridges and valleys will simultaneously be formed inthe surfaces joined so that these surfaces are further enlarged, therebyincreasing the strength of the joint.

In the manner described, packagings of foam polystyrene are produced forthe first time. The reason for this successful progress is that theproperty which was earlier considered an insurmountable obstacle to thesimple fastening together of two surfaces to be joined, viz theinsulating ability of the material, is exploited by the presentinvention to maintain the thin layer of molten thermoplastic material ina molten state for a time sufiicient to permit withdrawing the heatingmembers and putting together the surfaces to be joined and causing themsecurely to adhere together. It Will be realized that the material musthave a certain rigidity to permit being treated by the process accordingto the invention.

Packages manufactured in the manner described above possess manyadvantages, not the least of which is the relatively low cost ofproduction. However, the butt weld at the corner of the shell which hasproved disadvantageous in certain instances in that the packages mayrupture along this weld when subjected to internal pressure that mayarise, for instance, if the package is subjected to heavy impact loadingsuch as may result from rapid deceleration after a free fall. This isparticularly true when the package is filled with a liquid whichproduces relatively high hydrostatic pressures within the package whenthe package is subjected to impact loading. On such an occasion, thepackages tend to take a spherical shape, resulting in the weld beingsubjected to rather severe bending stresses combined with increased hoopor tensile stresses which may result in rupture of the welded joint. Atthe same time, the butt weld in the corners of the package may beadvantageous for packaging carton products. For example, frozen foodssuch as meats and vegetables will retain their shape and, therefore, donot tend to rupture the carton when subjected to heavy impact loading.However, to remove such food from the carton, it is advantageous tocompletely remove a side of the package, and the butt joint in thecorner of the carton then becomes an asset.

Another feature of the package produced according to the methoddescribed above is that, upon melting of the surfaces to be joined,polymers are released which, due to their high density with respect toambient air, tend to collect in the free space above a product disposedin the package. This may be insignificant in certain cases butdisadvantageous if the package contains certain foodstuffs of milk orflour contents since the free polymers may have a negative effect ontaste and smell. In fact, certain countries have regulations stipulatingthe amount of free polymers permissible in a food product.

The above-mentioned possible weaknesses or disadvantages of the cartonsmanufactured by the process illustrated in FIGS. 1-8 and described aboveare avoided in the package and method illustrated in FIGS. 9-17. In thissecond embodiment, a package is produced which withstands impacts andinternal pressures, and is useful for all foodstuffs without anydeleterious effect on their taste or smell. This is accomplished byinitially forming an open-ended tubular body, or shell, by wrapping asheet of the foamed thermoplastic material about a preformed mandrel insuch a way that the meeting edges will slightly overlap, thenintroducing a heating means obliquely between the overlapped, slightlyspaced edges for simultaneous melting of the outer corner of one edgeand the inner corner of the other edge to produce parallel joiningsurfaces so that an overlap weld is obtained after the surfaces havebeen brought together. If the body is formed with corners, the weld isspaced from these corners. To avoid collection of free polymers in thepackage, use is made of a top and/or bottom cover panel portion whichhas a peripheral recess extending. completely around said portion so asto form a plug projecting into the open end of the tubular body. Thecover panel is welded to the shell with the use of pointed heating meanswhich are employed to melt a V-shaped groove around the juncture of theshell and the cover panel, respectively, with pressure being applied tothe cover panel to close the V-shaped groove and form a continuous weld.

Referring specifically to FIGS. 911 a rectangular mandrel 110 withrounded corners is shown in cross section. A sheet of foamthermoplastic, preferably foam polystyrene, is wrapped around themandrel 110 so as to form the body of a package of generally rectangularcross section. The abutting edges of the body blank 111 which extendtransversely of the plane of the drawing slightly overlap, as willappear from FIG. 9, one edge being placed close to and the other edgeabove a recess 112 formed in the mandrel. After the sheet 111 has beenso placed, a heating means in the form of a slightly wedgeshaped heatingjaw 113 is introduced between the edges so that the outer corner of oneedge and the inner corner of the other edge and the closely adjoiningportions of the sheet edges are melted by direct contact with theheating jaw. The heating jaw is moved towards the mandrel 110 to such anextent that its point will penetrate into the recess 112. After a layerof melted plastic material of the requisite thickness has been formed,the heating jaw 113 is rapidly removed and the edges quickly broughttogether and subjected to pressure against the mandrel by means of amolding plate 114. The above principle can be applied in different ways,e.g., either by placing sheets one at a time on the mandrel, welding andthen removing them from the mandrel, or by wrapping an elongate stripcontinuously about the core and causing it while being pulled along thecore to pass a heating jaw and a subsequent pressure roller.

As will readily be seen, the joint of the tubular body is spaced fromthe corner thereof, which results in that, if a package having such abody is subjected to a heavy impact, the joint will be exposed primarilyto tensile or hoop stress, with the result that the joint will withstandconsiderably heavier loads resulting from impact than if the joint hadbeen situated at a corner of the shell where it would also be subjectedto relatively high bending loads.

FIGS. 12-14 illustrate how a cover is placed on a container afterfilling thereof in order to prevent or minimize free polymers fromcollecting in the space between the cover and the product filled intothe container. On this occasion use is made of a cover 120 of particularconfiguration with a recess 121 extending completely around the coverperiphery so as to form a thickened plug portion 122 which, when thecover is placed on the tubular body of a packaging, projects into andcloses the open end of the body. A cover of this type can be placed on apackage conveyed on a conveyer belt directly after a product has beenfilled into the packaging, whereby any risk of spillage of the packagecontents during the continued movements on the conveyer belt'isobviated.

The cover 120 is welded to the body 111 with the aid of a plurality ofheating jaws 123 having wedge shaped or pointed ends which are pushedinto the joint between the end surface of the shell facing the cover andthe bottom of the recess 121. Movement of the jaws 123 are preferablysubstantialy parallel with the plane of the cover 120, as illustrated inFIG. 13. This will melt a portion of the body to form an obliquelyupwardly and outwardly facing surface on a portion of the cover to forman obliquely downwardly and outwardly facing surface on the cover 20;however, due to the cover portion 122 projecting into the interior ofthe shell, the space within the package will not come into directcontact with the molten plastic. In conventional manner, a shaping tool124 is then pushed down onto the upper end of the packaging after theheating jaws have been removed,

as is shownin FIG. 14. The peripheral edge of the cover preferablyprojects slightly from the outer boundary surface of the body, as willbe seen in FIG. 12, whereby the projected wedge shaped periphery of thecover is folded downwardly to close the V-shaped groove and bring theshaped surfaces together to be joined with the folded portion of thecover forming, in effect, a hinge joining the top panel and the bodytogether with the welded joint being in the wall of the body as shown inFIG. 14. In FIGS. 12 and 13, only two heating jaws have been shown, butit is readily understood that if a container of rectangular crosssection is concerned, a further pair of heating jaws will be arranged soas to be movable at right angles to the pair of heating jawsillustrated.

The cover illustrated in FIG. 12 can be simply produced with theapparatus illustrated in FIG. 15, which comprises a water-cooled fixturewhich in longitudinal section is in the form of an inverted U and has across sectional shape corresponding to that of the package to bemanufactured. An infrared heater 131 is fastened to the inner side ofthe web portion of the U. By placing the fixture 130 on a panel of foamplastics and applying heat to the central portion, it is possible torealize an after-expansion of the plastics material exposed to theinfrared heat, yielding a cover of the type shown in FIG. 12, with anupwardly projecting central plug portion 122. Alternatively, the covermay be produced by commencing with a sheet of fully expanded foammaterial and applying heat and pressure to the peripheral edge portionto initialy soften and compress the material to form the peripheralrecess 121, then cooling the material to retain it in this condition.

A cover of the type shown in FIGS. 12-14 can be utilized in severalways, e.g., it may be formed with a delivery opening which can be closedby means of a readily detachable strip 141 as shown in FIGS. 16 and 17.The strip, which is preferably of impact-resistant plastic, is-preshapedwith closure means 142 which, before application of the cover 120 on thecontainer, is placed in the opening 140 in the cover so as to sealinglypenetrate thereinto. Preferably, the opening 140 in the cover is ofupwardly and inwardly tapering shape, as shown in the drawing, and theclosure portion of the strip has a complementary shape. After the coverhas been placed on the container and secured thereto by the weldingprocess described, the free end of the strip at the shaping of the jointby means of a member 124 will be pressed down against the side wall ofthe packaging, as is shown in FIG. 17, in which position the end of thestrip can be easily grapsed and pulled upwards to uncover the opening inthe cover. The closure portion of the strip is not destroyed by thistearing open and it can, therefore, be used again for reclosing theopening because of the configuration illustrated.

Of course, the packaging manufactured need not have the shape of aright-angled parallelepiped, but may also be cylindrical, spherical etc.It may also very well have the shape of a bottle. By this process is ispossible in a relatively simple apparatus to produce rigid or semi-rigidpackages at a considerably lower price than in the complicated machineshitherto used. The plastic material need not necessarily be foampolystrene but may also be any other foam plastic material havingapproximately the same rigidity. It should also be stresssed that it ispossible to treat, instead of the one-ply polystyrene blanks describedin the foregoing, laminated blanks of foam plastics material by theprocess according to the invention. Thus packages comprising an outerlayer of foam polystyrene and an associated somewhat softer inner layerof foam polyethylene, have proved extremely advantageous whenever ahigher inner or outer pressure may be expected, for instance because ofthe nature of the material enclosed in the package or because of thepackage being exposed to careless handling.

While I have disclosed and described preferred embodiments of myinvention, I wish it understood that I do not intend to be restrictedthereto, but that I do intend to include all embodiments thereof whichwould be apparent to one skilled in the art and which come within thespirit and scope of my invention.

I claim:

1. A process for manufacturing fluid tight packages from rigid foamedthermoplastic material comprising the steps of forming an open-endedtubular body member from said foamed thermoplastic material andsubsequently closing at least one open end of said tubular body with aclosure panel member formed from said foamed thermoplastic material bypositioning said closure panel in juxtaposed relation to said at leastone open end, simultaneously melting the edge portion of said closurepanel around its entire periphery and the juxtaposed end portion of saidtubular body around its entire periphery to form cooperating beveledsufaces having a layer of molten plastic material thereon extendingaround said closure panel and said body, respectively, and pressing saidbeveled surfaces into contact with one another around their entireperiphery substantially simultaneously and while said plastic materialthereon is still in the molten state to thereby form a continuous,strong, hermetically sealed joint between said closure panel and saidtubular body.

2. The process defined in claim 1 wherein the step of closing at leastone open end of said tubular body includes the step of initially closingone end of said tubular body, and subsequently closing the other openend by following the same procedural steps.

3. The process as defined in claim 1 wherein adjacent portions of saidbeveled surfaces are substantially parallel to one another-and inclinedwith respect to the longitudinal axis of said body portion.

4. The process as defined in claim 1 wherein said foamed thermoplasticis foamed polystyrene.

5. The process as defined in claim 1 further comprising the step ofpressing a shaping member into contact with said joint to shape thejoint and to wipe any excess of molten plastic from the joint.

6. The process as defined in claim 5 wherein said step of melting saidedge portion of said closure and said adjacent portion of said tubularbody comprises contacting said portions within a beveled member havingforming surfaces thereon disposed at an angle corresponding to the angledesired for said beveled surfaces.

7. The process as defined in claim 6 wherein said forming surfaces arecorrugated whereby said beveled surfaces are formed with complementaryundulated surfaces to thereby increase the area of contact therebetween.

8. The process as defined in claim 1 wherein said beveled surfaces areinitially formed with adjacent portions thereof disposed in planesinclined with respect to one another, and wherein said step of pressingsaid beveled surfaces into contact with one another includes the step ofbending the portion of one of said members adjacent one of said beveledsurfaces to position said beveled surfaces in parallel contactingrelation.

9. The process as defined in claim 8 wherein said closure panel memberincludes a central portion dimensioned to telescope into said at leastone end in contact with the inner surface of said tubular body, saidcentral portion lending radial support to said at least one open endduring said step of positioning said beveled surfaces in parallelcontacting relation.

10. The process defined in claim 1 wherein the step of forming saidtubular body comprises wrapping a sheet of said foamed thermoplasticmaterial about a preformed core and positioning the adjacent edgesthereof in slightly overlapping spaced relation, simultaneously meltinga portion of said adjacent edges along their entire length whilemaintaining said edges in said spaced relation to form substantiallyparallel beveled edges having a layer of molten plastic materialthereon, and pressing said substantialy parallel beveled edges togetherwhile the plastic material thereon is still in the molten state tothereby form a continuous, strong, hermetically sealed joint extendingthe full length of said body.

11. The process as defined in claim 10 wherein said tubular body isgenerally rectangular in cross section, and wherein said sealed jointextending the full length of said body is positioned in a panel of saidbody in spaced relation to the corner portions thereof.

12. A process for manufacturing packages from rigid foamed thermoplasticmaterial comprising the steps of forming an open-ended tubular body fromsaid foamed thermoplastic material, forming a separate closure panelfrom said foamed thermoplastic material, said separate closure panelhaving a thickened central portion adapted to telescope into an open endof said body and engage the inner surface thereof and a peripheralflange extending outward from said thickened portion, positioning saidclosure panel onto one open end of said body with said thickened portiontelescoping therein, contacting said peripheral flange and said one openend of said body portion with heating means substantially simultaneouslyaround their entire peripheries to melt a portion of said foamedtheromplastic material to form cooperating beveled surfaces extendingtherearound and having a layer of melted thermoplastic material thereon,removing said heating means, and immediately pressing said beveledsurfaces together around their entire periphery substantiallysimultaneously and while said layers of thermoplastic material remainmelted to thereby form a continuous, strong, hermetically sealed jointbetween said body portion and said closure panel.

13. The process as defined in claim 12 wherein said step of pressingsaid beveled surfaces together includes the step of pressing a shapingmember against said joint throughout the length thereof to shape saidjoint and to wipe any excess molten material forced therefrom.

14. The process as defined in claim 12 wherein said closure panel isinitially positioned onto said one open end with said peripheral flangein engagement with said open end, and wherein said step of melting aportion of said closure panel and said body portion comprises melting asubstantially V-shaped groove around the periphery of said body and saidpanel with the surface defining one leg of the V being formed in saidbody portion wall and the surface defining the other leg of said V beingformed in said peripheral flange.

15. The process as defined in claim 14 wherein the depth of saidV-shaped groove is substantially equal to the wall thickness of saidbody portion, said step of pressing said beveled surfaces togetherincludes the step of bending the peripheral edge portion of said closurepanel downwardly along said body portion.

16. The process as defined in claim 15 wherein said step of pressingsaid beveled surfaces together includes the step of pressing a shapingmember into contact with said joint to shape the joint and to wipe anyexcess molten plastic material from the joint.

17. The process as defined in claim 12 wherein the step of forming saidbody portion comprises wrapping a sheet of said foamed thermoplasticmaterial about a preformed core and positioning the adjacent edgesthereof in slightly overlapping spaced relation, simultaneously meltinga portion of said adjacent edges along their entire length whilemaintaining said edges in said spaced relation to form-substantiallyparallel beveled edges having a layer of molten plastic materialthereon, and pressing said substantially parallel beveled edges togetherwhile the plastic material thereon is still in the molten state tothereby form a continuous, strong, hermetically sealed jointextending-the full length of said body.

18. The process as defined in claim 17 wherein said body portion isgenerally rectangular in cross section, and wherein said sealed jointextending the full length of said body 1 1 ,is positioned in a panel ofsaid body in spaced relation to the corner portions thereof.

19. The process as defined in claim 12 further comprising the steps offorming said closure panel from a blank of foam plastic sheet byclamping and cooling the peripheral edge portion of said blank andapplying heat to the central portion thereof to thereby further expandsaid central portion.

20. The process as defined in claim 19 further comprising the steps offorming a dispensing and filling opening in said closure panel, andapplying a removable and recl osable closure member to said opening.

21. The process as defined in claim 21 further comprising the steps offorming said closure panel from a blank of fully expanded foam plasticsheet by heating and compressing the peripheral edge portion only ofsaid blank, and subsequently cooling said peripheral edge portion to setit in the compressed condition.

References Cited UNITED STATES PATENTS 3,411,969 11/1968 Ragen et a1.156-227 3,317,114 '5/ 1967 Ragen et a1. 156211 X 12 3,282,766 11/1966Wright 15 -304 3,356,552 12/1967 Pearl 15669 -3,712,844 1/1973 Rattene161 156--77X 3,391,619 7/1968 Beregi 156-218 X 5 3,443,007 5/1969 Hardy15678 X 3,615,965 10/1971 Smith et a1. 156 69 3,400,040 9/1968 Osgood1562l6 X 2,770,406 11/1956 Lane ,156 -78X 10 3,052,926 9/1962 Quinche81231 156196X 3,391,045 7/1968 Mojonnieretal 156304 3,625,785 12/1971-Loberod 15669 3,354,603 11/1967 Katzen 6161. 53 39 15 FOREIGN PATENTS1,597,462 6/1970 France; 156-227 RALPH S. KENDALL, Primary Examiner 20B. J. LEWRIS, Assistant Examiner US. Cl. X.R.

